Posted tagged ‘geometry’


August 23, 2011

AutoCAD Freestyle is built on the AutoCAD platform and is compatible with AutoCAD’s DWG file format. This means that in AutoCAD Freestyle you can open a file created in AutoCAD or AutoCAD LT add sketches, notes, and drawing enhancements and save completing workflow and round-trip with other DWG-based applications.


But while AutoCAD requires quite a lot of training most anyone can get started using AutoCAD Freestyle right away thanks to its Integrated learning tools.

When a DWG file from another application is opened in AutoCAD Freestyle, the original objects cannot be edited. That is, all geometry and text are on a locked layer.

AutoCAD Freestyle only opens one paper space layout at a time. If a DWG file created in another application contains multiple paper space layouts, the user can select a single layout to use.

DWG files created in other applications that contain 3D views may be somewhat limited in their functionality when opened and viewed in AutoCAD Freestyle.

All text, geometry, and fill elements added to a file using AutoCAD Freestyle are automatically placed on new, AutoCAD Freestyle-specific layers.

If you are an AutoCAD (or other DWG-based software application) user, and you plan to send a DWG file to a user who is unfamiliar with DWG drawings, the best approach is to create a DWG file with a single viewport in a paper space layout.

There is no way to add new symbols (blocks) to the library within the application. But the ToolPalette file AcTpCatalogacadfs.atc can be manually edited to achieve this. Dynamic blocks are supported.

AutoCAD Freestyle saves to AutoCAD 2007 DWG file format but can open AutoCAD 2010 DWG file format files. It looks like this first release is based on AutoCAD 2010 as 18.0 is the interval version number and not 18.1 as in AutoCAD 2011.

AutoCAD freestyle Exercise 1:

05-free autocad drawings-free autocad exercises-free autocad blocks


AutoCAD freestyle Exercise 2:

01-free autocad drawings-free autocad exercises-free autocad blocks

AutoCAD freestyle Exercise 3:

02-free autocad drawings-free autocad exercises-free autocad blocks

AutoCAD freestyle Exercise 4:

03-free autocad drawings-free autocad exercises-free autocad blocks

AutoCAD freestyle Exercise 5


04-free autocad drawings-free autocad exercises-free autocad blocks

You can use this way. If you’re creating 2D drawings and 3D drawings. If you follow this way, you’re saving a lot of time.

The new way of creating CAD drawings is all about creating a 3D drawing first and then using that drawing to create your 2D drawing. In this course is explained how it is done. More. There is even explained how you can add dimensions to your 2D drawing.

Let’s make a good start. We start with creating a 3D drawing. It’s going to be a simple drawing. But that doesn’t matter.

CAD 3D drawing 1:

03-autocad drawings-design-exercises

CAD 3D drawing 2:01-autocad drawings-design-exercises

CAD 3D Drawing 3:02-autocad drawings-design-exercises


August 23, 2011

Crystalline Materials:

  • A crystalline material is one in which the atoms are situated in a repeating (or) periodic array over large atomic distances.




Non Crystalline Materials:

  • Materials that do not crystallize are called non-crystalline (or) Amorphous materials


Space Lattice:

  • Lattice is the regular geometrical arrangement of points in crystal space.

01-lattice-crystal structure


  • The atoms arrange themselves in distinct pattern in space is called a Space Lattice.
  • Atoms in crystalline materials are arranged in a regular 3 – Dimensional repeating pattern known as Lattice Structure.
  • They are divided by network of lines in to equal volumes, the points of intersection are known as Lattice Points.


Unit Cell:

01-unit cell

  • It is the smallest portion of the lattice which repeated in all directions.
  • 3D visualization of 14 Space Lattices are known as Bravai’s Space Lattice.
  • If a unit cell contains lattice points only at it’s corners, then it is called Primitive Unit Cell (or) Simple Unit Cell.
  • Three edge length x,y, & z and three interaxial angles α, β, & γ are termed as Lattice Parameters.


Crystal System:

  • It is a scheme by which crystal structures are classified according to unit cell geometry.


Types of Crystal Systems:

    • Cubic
    • Tetragonal
    • Hexagonal
    • Orthorhombic
    • Rhombohedral
    • Monoclinic
    • Triclinic


Crystal Systems


Simple Crystal Structure:

Body Centered Cubic Structure (BCC)

  • Unit cell contains 2 atoms
  • Lattice Constant a= 4r / √3, where r is atomic radius
  • Atomic packing factor APF = 0.68
  • Metals are Vanadium, Molybdenum, Titanium, Tungsten

0I-bcc-structure-body center cubic02-bcc-structure-body center cubic

03-bcc-structure-body center cubic


Face Centered Cubic (FCC)

  • Unit cell contains 4 atoms
  • Lattice Constant a= 4r / √2, where r is atomic radius
  • Atomic packing factor APF = 0.72
  • FCC structures can be plastic deformed at severe rates
  • Metals are Copper, Aluminum, Phosphorous, Nickel, Cobalt etc

02-fcc-structure-face center cubic-unit cell

0I-fcc-structure-face center cubic-unit cellHexagonal Closed Packed Structure (HCP)

  • Unit cell contains 3 atoms
  • Axial ratio c/a, where ‘c’ is Distance between base planes, ‘a’ is Width of Hexagon
  • Axial Ratio varies from 1.58 for Beryllium to 1.88 for Cadmium (Therefore  a=2.9787, c=5.617)
  • Atomic packing factor APF = 0.74
  • Metals are Zinc, Cadmium, Beryllium, Magnesium etc

0I-hcp-structure-Hexagonal close packed-unit cell

0I-hcp-structure-hexagonal close packed

0I-hcp ball-structure-Hexagonal close packed-unit cell



Crystallographic Planes and Directions

The Layers of atoms in the planes along which atoms are arranged is known as “Atomic” (or) “Crystallographic planes”.

Miller Indices:

Miller Indices is a system of notation that denotes the orientation of the faces of a crystal and the planes and directions of atoms within that crystal.

Miller Indices for Planes:

1. The (110) surface

02-miller indices-crystalographic planes


Intercepts :   a , a , ∞

Fractional intercepts :   1 , 1 , ∞

Miller Indices :   (110)


2. The (111) surface

03-miller indices-crystalographic planes


Intercepts :   a , a , a

Fractional intercepts :   1 , 1 , 1

Miller Indices :   (111)

The (100), (110) and (111) surfaces considered above are the so-called low index surfaces of a cubic crystal system.


3. The (210) surface

04-miller indices-crystalographic planes


Intercepts :   ½ a , a , ∞

Fractional intercepts :   ½ , 1 , ∞

Miller Indices :   (210)